Severe emphysema is a debilitating disease that limits quality of life of patients and represents an end state of Chronic Obstructive Pulmonary Disease (COPD). It is believed that 3.5 million people in the US have the severe emphysematous form of COPD, and it is increasing in both prevalence and mortality. Current treatment methods for severe emphysema include lung volume reduction (LVR) surgery, which is highly invasive, and can be risky and uncomfortable for the patient. New treatment methods for treating emphysema include bronchoscopy guided LVR (BLVR) devices such as one-way valves that aim to close off ventilation to the diseased regions of the lung, but maintain ventilation to healthier lung. Bronchoscopy-guided techniques have the promise to be less invasive, less costly and more highly accurate treatments for patients with severe disease and improve the quality of life of severe emphysema patients.
Emphysema can present itself in various disease forms (i.e., phenotypes). Predicting the right treatment for these patients at the appropriate time in the disease process likely depends on the phenotype of the disease. Imaging techniques provide an in-vivo mechanism to objectively quantify and characterize disease phenotypes and can be used in the patient selection process for the various procedural options. Quantitative imaging biomarkers can be used to effectively phenotype disease and therefore predict those patients most likely to respond to the targeted treatment options. By triaging patients to the appropriate therapy, there exists a greater promise for a positive impact on patient outcome, reduced healthcare costs, and replacing more invasive procedures like LVR surgery in treating patients with severe emphysema.
Fissures are important anatomical structures within lungs. It is believed that fissures have an effect on regional lung mechanics. For example, adjacent lobes can slide against each other at fissure interfaces, which provide a means to reduce lung parenchymal distortion. In addition, intact fissures play an important role in reducing collateral ventilation among lobes and the spread of diseases. Recently, fissure integrity has emerged as a strong biomarker to predict the response to interventional emphysema therapies including localized lung volume reduction. In short, if the fissure of the lung is intact, an obstructive device like a valve will more likely produce a seal leading to the atelectasis (i.e., collapse) of the diseased lung sub-region. Without an intact fissure, there is a possibility of collateral ventilation and the likelihood of success of the procedure may be reduced. However, accurately detecting and characterizing fissures in diseased lungs is difficult.
Methods of detecting fissures include fitting the existing portions of the fissures to a lobar atlas (as described in E. M. van Rikxoort et al., “A method for the automatic quantification of the completeness of pulmonary fissures: evaluation in a database of subjects with severe emphysema,” European radiology, (2011): 0-7, for example) or by an extrapolation of the existing portion of the fissure to the absent portion (as described in J. Pu et al., “Computerized assessment of pulmonary fissure integrity using high resolution CT.,” Medical Physics, 37(9), (2010): 4661-4672, for example). However, neither of these approaches makes full use of the anatomic information available in the image data.